.TH std::expected::operator->,std::expected::operator* 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::expected::operator->,std::expected::operator* \- std::expected::operator->,std::expected::operator*

.SH Synopsis
   T is not cv void
   constexpr const T* operator->() const noexcept;   \fB(1)\fP (since C++23)
   constexpr T* operator->() noexcept;               \fB(1)\fP (since C++23)
   constexpr const T& operator*() const& noexcept;   \fB(2)\fP (since C++23)
   constexpr T& operator*() & noexcept;              \fB(2)\fP (since C++23)
   constexpr const T&& operator*() const&& noexcept; \fB(2)\fP (since C++23)
   constexpr T&& operator*() && noexcept;            \fB(2)\fP (since C++23)
   T is cv void
   constexpr void operator*() const noexcept;        \fB(3)\fP (since C++23)

   Accesses the expected value contained in *this.

   1) Returns a pointer to the contained value.
   2) Returns a reference to the contained value.
   3) Returns nothing.

   The behavior is undefined if this->has_value() is false.

.SH Parameters

   \fI(none)\fP

.SH Return value

   Pointer or reference to the contained value.

.SH Notes

   These operators do not check whether the optional contains a value! You can do so
   manually by using has_value() or simply operator bool(). Alternatively, if checked
   access is needed, value() or value_or() may be used.

.SH Example


// Run this code

 #include <cassert>
 #include <expected>
 #include <iomanip>
 #include <iostream>
 #include <string>

 int main()
 {
     using namespace std::string_literals;

     std::expected<int, std::string> ex1 = 6;
     assert(*ex1 == 6);

     *ex1 = 9;
     assert(*ex1 == 9);

     ex1 = std::unexpected("error"s);
     // *ex1 = 13 // UB, ex1 contains "unexpected" value
     assert(ex1.value_or(42) == 42);

     std::expected<std::string, bool> ex2 = "Moon"s;
     std::cout << "ex2: " << std::quoted(*ex2) << ", size: " << ex2->size() << '\\n';

     // You can "take" the contained value by calling operator* on an rvalue to expected

     auto taken = *std::move(ex2);
     std::cout << "taken: " << std::quoted(taken) << "\\n"
                  "ex2: " << std::quoted(*ex2) << ", size: " << ex2->size() << '\\n';
 }

.SH Possible output:

 ex2: "Moon", size: 4
 taken: "Moon"
 ex2: "", size: 0

.SH See also

   value         returns the expected value
                 \fI(public member function)\fP
   value_or      returns the expected value if present, another value otherwise
                 \fI(public member function)\fP
   operator bool checks whether the object contains an expected value
   has_value     \fI(public member function)\fP
   error         returns the unexpected value
                 \fI(public member function)\fP
